1. Field of the Invention
The present invention relates to methods and apparatus for dispensing and distributing discrete small geometric solids and more particularly concerns automatic handling and positioning of small geometric solids in a pre-selected pattern.
2. Description of Related Art
It is often necessary to distribute small geometric solids for use in various types of processes. Distribution of a number of similar items to selected areas or in selected patterns is a frequently useful operation. For example, in some types of manufacture of electronic circuit components, small components and chips are positioned on a substrate in pre-selected patterns or locations and secured to the substrate by soldering. Leadless chip carriers are placed on a solder bump that is carried by a substrate and then soldered in place, thereby attaching the carriers to the substrate. At present this procedure of attaching small items, such as leadless chip carriers, solder preforms, components and chips to the substrate is carried out by two steps: first, the manual placement of individual spherical solder preforms in a pre-selected pattern or in pre-selected locations at which the component chips or chip carriers are to be attached. The manual positioning of such small elements (preforms are often in the range of 0.010 inches in diameter) and maintaining all of them in place while others are manipulated into position is tedious, laborious, time consuming, expensive and subject to human error. Additionally, electrostatic forces can cause clumping of items, making it difficult to place single discrete items at each location. Second, the components chips and chip carriers are placed manually or with the aid of a vacuum pick up. To aid an operator in placing the chips (or chip carriers), the chips are placed in a pallet having preformed recesses for retaining the chips. A vacuum pick up removes the chips one at a time for placement on the board or substrate where they will be attached by solder.
Accordingly, it is an object of the present invention to provide for distribution or placement of small items or geometric solids while avoiding or minimizing problems set forth above.